Oracle：類似於描述命令的腳本

Question

我被要求創建一個基本上與describe命令做同樣事情的腳本。 我已經想出瞭如何編寫腳本並獲得我想要的輸出，但第二部分的任務是「複製describe命令的格式」我很難過，是否真的有一種方法可以簡單地複製該格式？

Answer 1

假設你的查詢是一樣的東西（請注意，我沒有打擾天天看不同的數據類型）

select column_name "Name", 
     (case when nullable = 'N' 
      then 'NOT NULL' 
      else null 
     end) "Null?", 
     (case when data_type = 'DATE' 
      then data_type 
      when data_type = 'NUMBER' and data_scale > 0 
      then data_type || '(' || data_precision || ',' || data_scale || ')' 
      when data_type = 'NUMBER' and data_scale = 0 
      then data_type || '(' || data_precision || ')' 
      when data_type = 'VARCHAR2' 
      then data_type || '(' || data_length || ')' 
     end) "Type" 
    from dba_tab_cols 
where table_name = 'EMP' 
order by column_id 

可以發出一些SQL * Plus命令的輸出

SQL> column "Nmae" format a30; 
SQL> column "Null?" format a8; 
SQL> column "Type" format a30; 

格式化

然後您的查詢的輸出將與DESCRIBE命令的輸出匹配

SQL> ed 
Wrote file afiedt.buf 

    1 select column_name "Name", 
    2   (case when nullable = 'N' 
    3    then 'NOT NULL' 
    4    else null 
    5   end) "Null?", 
    6   (case when data_type = 'DATE' 
    7    then data_type 
    8    when data_type = 'NUMBER' and data_scale > 0 
    9    then data_type || '(' || data_precision || ',' || data_scale || ')' 
10    when data_type = 'NUMBER' and data_scale = 0 
11    then data_type || '(' || data_precision || ')' 
12    when data_type = 'VARCHAR2' 
13    then data_type || '(' || data_length || ')' 
14   end) "Type" 
15 from dba_tab_cols 
16 where table_name = 'EMP' 
17* order by column_id 
SQL>/

Name       Null? Type 
------------------------------ -------- ------------------------------ 
EMPNO       NOT NULL NUMBER(4) 
ENAME         VARCHAR2(10) 
JOB          VARCHAR2(9) 
MGR          NUMBER(4) 
HIREDATE        DATE 
SAL          NUMBER(7,2) 
COMM         NUMBER(7,2) 
DEPTNO         NUMBER(2) 

8 rows selected.